Sir Tim Berners-Lee, the computer scientist who created the world wide web, has called for a “full and frank public debate” over internetsurveillance by the National Security Agency and its British counterpart, GCHQ, warning that the system of checks and balances to oversee the agencies has failed.

As the inventor of the global system of inter-connectivity known as the web, with its now ubiquitous www and http, Berners-Lee is uniquely qualified to comment on the internet spying revealed by the former NSA contractor Edward Snowden.

In an interview with the Guardian, he expressed particular outrage that GCHQ and the NSA had weakened online security by cracking much of the online encryption on which hundreds of millions of users rely to guard data privacy.

He said the agencies’ decision to break the encryption software was appalling and foolish, as it directly contradicted efforts of the US and UK governments to fight cybercrime and cyberwarfare, which they have identified as a national security priority. Berners-Lee also said it was a betrayal of the technology industry.

In contrast to several senior British politicians – including the prime minister, David Cameron – who have called for the Guardian to be investigated over reporting of the Snowden leaks, Berners-Lee sees the news organisation and Snowden as having acted in the public interest.